Gill Disease (Gill Inflammation / Branchial Disorder)

About this condition

A syndrome in which the gills become inflamed or functionally impaired due to bacterial infection, parasites, or poor water quality, causing respiratory distress. Because the gills are essential for oxygen exchange, progressive damage leads to rapid deterioration.

Common symptoms

• Gasping at the water surface (oxygen-deprived-like breathing)
• Asymmetric gill movement or one gill staying permanently open
• Gills appearing abnormally red or pale
• Sluggish movement and separation from the group

Common causes

• Bacterial infection such as Columnaris
• Parasitic infestation of the gills by ciliates or monogeneans
• Water quality deterioration (elevated ammonia or nitrite levels)
• Overcrowding, oxygen depletion, or low dissolved oxygen

Prevention (husbandry & daily care)

Prevent ammonia and nitrite buildup through regular water changes, avoid overcrowding, and ensure adequate dissolved oxygen. Using aeration and maintaining stable water temperature and pH are effective preventive measures.

Related species guide

When to see a vet

What can a specialist store do?

Gill disease can be caused by a combination of bacteria, parasites, and water quality issues, making it difficult to identify the cause from symptoms alone. Consulting a specialist aquarium store or experienced keeper provides practical advice on observing gill condition and checking key water parameters such as ammonia, nitrite, and dissolved oxygen. When multiple fish show similar symptoms, reviewing the overall tank environment is the priority.

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